Spontaneous formation of liquid crystalline phases and phase transitions in highly concentrated plasmid DNA
Journal article, 2011
The liquid crystalline (LC) properties of two supercoiled plasmid DNA samples, pBSK (2958 bp) and pGEM (3000 bp), have been studied using polarised light microscopy (PLM), circular dichroism (CD) and UV-Vis spectroscopy. The influence of methods of isolation on plasmid LC behaviour is described, and using PLM we have demonstrated the spontaneous formation of cholesteric fingerprint-like textures. Preliminary studies of LC phase transitions in pGEM show the irreversibility of LC phase formation, as a consequence of changes in the tertiary structure of supercoiled plasmids. Using UV-Vis spectroscopy a hyperchromic effect was observed with increasing temperature. The CD spectra clearly showed structural changes, and probably mismatching of DNA bases, during cooling. Finally, we have observed an irreversible phase transition in plasmid DNA which is very different from that previously reported in linear DNA.
fingerprint-like texture
escherichia-coli
supercoiling
linking
supercoiled dna
dimensions
liquid crystal
isolation techniques
shock
phase transition
growth temperature
thermal-denaturation
cholesteric phase
nucleic acids
DNA
microscopy
circular dichroism
bacteria
hyperchromic effect
plasmid DNA
Author
Piotr Hanczyc
Chalmers, Chemical and Biological Engineering, Physical Chemistry
K. Matczyszyn
Wrocław University of Science and Technology
K. Pawlik
Ludwik Hirszfeld Institute of Immunology and Experimental Therapy of the Polish Academy of Sciences
AKademia Medyczna Wroclawiu
J. Olesiak
Wrocław University of Science and Technology
H. Leh
Laboratoire de Biologie et de Pharmacologie Appliquee
M. Buckle
Laboratoire de Biologie et de Pharmacologie Appliquee
Liquid Crystals
0267-8292 (ISSN) 1366-5855 (eISSN)
Vol. 38 4 461-468Subject Categories (SSIF 2011)
Chemical Sciences
DOI
10.1080/02678292.2011.552740